Bulbo's roots die when they hit the medium
 

I have young Bulbo Wilmar galaxy star (lobbii x dearei). A few months ago it started some new growths, but as soon as the new roots hit the medium they turn brown and die. It was repotted it in fresh sphag in the fall, and I water it with a weak dose of fertilizer (125ppm N) that most of my other orchids get. The top layer of sphag does get quite crunchy before the next watering, could that be the problem?

Hi Camille, I don't grow this hybrid but I suspect you're right about the dryness of the sphag. Most of my bulbos seem to love moist sphagnum around their roots and when I see root death it's often related to low moisture levels. You could also be having problems with salt build-up; 125 PPM N shouldn't be too high but you might have high TDS in your water prior to adding fertilizer. I would suggest flushing the medium really well and then keeping it moister overall. If that doesn't work then try changing out the sphag for fresh. Good luck!

--Nat

I agree, I keep my potting medium pretty moist for my bulbo's. I usually water them at 1/4 strength fertilizer when I spray them but the misting system gives them several good sprays of RO water. Hope this helps!

I guess, I'll start misting the top layer everyday to keep it from getting dry before the rest dries.

Becca, you use 1/4 strength of what? Mine's a 6-6-7 (or something along those lines) so 1/4 is nearly nothing.

I use a 1/4 strength of the MSU type fertilizer for pure water, which is 13-3-15 8Ca-2M. Guess I'm affraid of burning the roots with to much fertilizer. I admit, I don't know much about bulbo's, just that mine are alive and bloom every so often for me...lol.

Camille, you might want to try "building up" the sphag around the base of the new pseudo bulb and allow the roots to grow into it. I don't usually use moss but in this type of situation that is what I do. This is the same Bulbophyllum. The roots of the pseudo bulb began growing toward the bark/CHC and I wanted to be sure they didn't die so I built a mound of moss around the base of the bulb.

Another thing to try if you don't want to mist or water every day: a small dish of water under the pot, refilled a day or two after the plant drains it. I know this is usually a no-no with orchids, but I've tried it with a couple of bulbos on the advice of a much-awarded grower and the plants respond very well.

--Nat

Both your ideas are interesting! I'll definitately add some sphag up to the bulbs (but won't really be a mound since the bulbs are already pretty close to it)

Nat- That's very good to know! Was this with sphag potted plants or another medium? At this point I'm not too worried about killing the roots in the pot, there aren't many. It was one of the plants that suffered a bit (kept way too dry) in the hands of the orchid sitter while I was in the USA for 5 months last year.

Hi Camille, so far I've tried this with bulbos in sphag, CHC, and a combo of the two. Most of them are in net pots so the roots get lots of air even when the medium stays wet. I suspect that the high moisture will cause the media to break down faster and necessitate sooner repotting. I've gotten a little bit of salt crust from evaporation, so I periodically remove the top sphag and replace it. I'm about to try some of my clumpier bulbos in S/H, which is supposed to work very well as long as the plants can be contained in the pots.

--Nat

I think I have a small net pot laying around. Somewhere. Just have to find it, lol!
I'd been thinking of putting it in S/H, but was afraid that I'd have the same problem with the top layer being too dry for the roots to successfully go down into the hydroton.